[Graham]

I agree with the rest probably about 12x montly earnings is about the max, unless you have something unique to offer (ie. a program on your site that does something and is considered an industry standard).

I would try to hold back things like search terms that you rank well for so that people don't steal this info for a similar type of site, etc. Its hard to attract a buyer if you are holding too much back. Good luck with the sale!